Leave-one-out, spatial-block, and independent validation

Leave-one-out asks how a measured location is predicted by nearly the full network. Spatial blocks ask about transfer into separated areas. Independent validation uses a separate sample and is not cross-validation. ps_validate() records exact training IDs, holdouts, support, failed predictions, seeds, and partition hashes. Compare designs only after stating the intended prediction task; none is automatically area-wide map accuracy.

loocv <- ps_validate(points, "IDW", "loocv", prediction_mode="direct")
blocks <- ps_validate(points, "IDW", "spatial_block", folds=5, seed=9)
independent <- ps_validate(points, "IDW", "independent",
                           validation_points=validation_points)